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Smartphone storage - how low can you go?

Perhaps matching the debate on sealed vs replaceable batteries as a design trend for our time is that of sealed memory. In other words, flash storage for applications, files, documents and media, which is of a fixed size and with no options for user expansion. Is sealed memory ultimately acceptable and, if so, is it possible to calculate a healthy minimum for 2014 devices?

Archetypal in the trend to sealed memory was/is the Apple iPhone, of course, though there were examples of the same idea going right back to the earliest days of PDAs and the first smartphones. For example, the Palm PDAs, the Psion Revo, the Nokia 7650 and classic N95 8GB. Those were, however, simpler days and the mission for a smartphone in 2013/2014 is very different, encompassing more, ever demanding roles. But how much memory/storage is enough?

Just to be clear, 'memory' in this context is NOT 'RAM', i.e. Random Access Memory, the working space for the running OS in your phone. Here, memory refers to flash storage, for files, apps and items which persist even if you turn the phone off.

We've seen some high profile examples of sealed memory in smartphone designs in recent times, often slightly controversial. For example, the Nokia E7 (from the Symbian world), a business 'Communicator' yet with no way to expand its paltry 16GB capacity; the Nokia Lumia 1020 (from the Windows Phone world), an imaging powerhouse that's ultimately limited by the way it fills up with your captured underlying 38MP photos and 1080p videos, again with no way to expand its 32GB internal disk; and the otherwise well respected LG G2 (from the Android world) and the equally well thought of Lumia 925, both shipping in most markets with just 16GB of non-expandable memory, a potentially crippling restriction.

Totally sealed - battery and memory capacity - the Lumia 1020. Even though videos are 200MB/min and photos are 20MB a pop...

One way around this, of course, is to do exactly what Apple has done and make many different versions of your smartphone, with varying capacities, and this has had some take-up by other manufacturers, e.g. LG and Google, producing two equally available versions of the new Nexus 5 (16GB and 32GB).

More commonly, manufacturers (perhaps responding to user feedback) have found ways to re-introduce microSD expansion into newer models - for example Nokia with the Lumia 625, 1520 and 1320, albeit that the extra capacity can't always be used to store every type of content.

It should be obvious that every smartphone user is different, and with subtly varying needs, making this feature something of a generalisation, but it is my contention that there are common factors and needs. By applying some knowledge of file and application sizes and more than a little common sense, it's possible to rationalise what the minimum storage capacity of a modern smartphone should be.

In no particular order(!):

Operating systemThe OS has to be stored somewhere, of course. Reckon on around 3GB for this (+/- a Gigabyte, depending on the device and OS).

OS useJust as a desktop OS has to have free space to work in, for its caches, swap and temporary files, so a phone OS needs working space too. Reckon on 100MB as an absolute minimum.

Email/social data/SMSEach type of data your phone handles has its own database, such as one for email, one for contacts, and so on. Add them all up and reckon half a Gigabyte, to be safe.

Web browser cacheMost people are familiar with the concept of a browser cache, i.e. somewhere to keep copies of web page resources that have been downloaded, ready for use later on (within a few days). Phone browsers are no different, allow for a Gigabyte for this at least.

ApplicationsWhich, or how many, apps are installed is a very personal thing, of course, but on my current phone (a Lumia 1020) I have around 1GB of applications (around 25 separate programs), so take this as fairly typical.

GamesThese are also, obviously, very personal, but the chances are that some of the bigger titles have been bought or downloaded in trial form. Again, sampling my own smartphone, I have around 2.5GB of games installed.

Country mapsOne of the unique things about Nokia's smartphones in particular is that the map data for entire countries can be downloaded and held offline. Assuming that you want at least your own country's roads installed, reckon on up to 500MB for these.

Office documentsAccessing offline Office documents is something of a niche activity these days, but most pf us have a few PDFs and Word files, at least, which are needed all the time. Say 100MB max for the lot.

Captured photosAssuming typical use (i.e. not me!), perhaps a photo a day for a year, so around 300 photos that might be stored on-phone at any one time. At worst case (on the 1020, at least) these can be up to 15MB each, so that's 4.5GB in total.

Captured videosI'll bet that most users take fewer videos than photos on their smartphone, but then again, the files are much larger. Assuming 20 clips of 30 seconds each, at 200MB/min, that's around 2GB worth of captured vids to stash away internally.

MusicYes, yes, streaming music is all the rage and, data permitting, I've been known to use these services sometimes, especially Nokia's rather tasty and revamped free MixRadio service. But most people, I suspect, like to have some offline music loaded, for when they're on the tube train or in the country, or forced into offline mode for some reason (e.g. in a hospital or plane). A dozen albums is probably a good guess here, so reckon on around 1.5GB (will depend wildly on bitrate and encoding used, of course!)

Nokia MixRadio offline mixesOn Windows Phone, at least, the aforementioned application enables you to keep some of your favourite mixes offline, though these tend to be quite small, around 100MB each. So perhaps allow for a couple of these too.

PodcastsA biggie for me, and probably most people reading this article. The vast majority of podcast listeners download the programmes (either on the smartphone or via some sideloading) and listen 'offline', which means some storage is needed. Say a dozen podcasts, average size 50MB, with perhaps the last two of each retained on the device - that's 1.2GB, all in all.

Movies/videosMaybe it's just me, but I doubt it. I love keeping a selection of my favourite music videos and documentaries on the phone, ready for consumption wherever I am and whatever the connectivity is like. It's a system that's proved itself again and again - for me, at least. Reckon on around 2GB at least for these at 720p resolution (say).

Add all of the above up - remember, we're assessing how capacious a device with sealed memory would need to be, for the average user - and you get 20.1GB.

Which rather puts the kibosh on all smartphones with a sealed 16GB mass memory - so that's the 16GB versions of the Lumia 925 and LG G2 out, for a start. Also the Nokia E7 from the Symbian world. And so on. The fact that 16GB is still a popular choice in the shops for 'sealed' smartphones probably reflects that most novice buyers don't exercise most of the functionality mentioned above. Certainly for people reading this article and who were nodding along throughout my list, take it from me and don't assume that you can live with a non-expandable 16GB.

Of course, thankfully, there are still plenty of designs which DO include a microSD card slot and some degree of expandability. Whatever your chosen platform, for example, captured photos, videos, sideloaded movies, music and often podcasts as well, can all be safely directed onto a microSD card. In fact, that's around 13GB of the 20GB just quoted, meaning that, with a card, you may even be able to get away with an 8GB 'sealed' device - as evidenced by a large number of Nokia Symbian and Windows Phone devices with 8GB mass memory plus microSD - a very popular combination between 2009 and 2013 and one borne out by my analysis here.

For 2014 smartphones with no expansion though, I'd suggest that 32GB is the minimum you should look for - don't look at 16GB variants just because they're 'cheaper'.

How close are my estimates to your own usage? Examples and data points welcomed. Have you bought a 16GB 'sealed' device and ended up regretting it?